1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a method for regulating the amount of liquid crystal in an LCD device manufactured by a liquid crystal dispensing method.
2. Discussion of the Related Art
Among ultra-thin flat panel displays having a thickness of several centimeters (cm), LCD devices have been generally used in notebook computers, monitors, spacecraft, airplanes, etc., because LCD devices have the advantageous characteristics of low power consumption and portability.
Hereinafter, a related art LCD device will be explained in detail.
FIG. 1 is a cross section view illustrating a related art LCD device. As shown in FIG. 1, the related art LCD device includes lower and upper substrates 10 and 20 facing each other with a predetermined interval therebetween, and a liquid crystal layer 40 formed between the lower and upper substrates 10 and 20 and sealed by a sealant 30.
Although not shown, the lower substrate 10 includes gate and data lines formed perpendicularly to define a pixel region, a thin film transistor as a switching element formed adjacent to a crossing of the gate and data lines, and a pixel electrode connected to the thin film transistor and formed in the pixel region.
Although not shown, the upper substrate 20 includes a light-shielding layer to prevent light leakage in areas except the pixel region, a color filter layer of red (R), green (G), and blue (B) to represent colors in the area corresponding to the pixel region, and a common electrode formed on the color filter layer.
The LCD device is manufactured by preparing the lower and upper substrates and forming a liquid crystal layer between the prepared lower and upper substrates. At this time, the liquid crystal layer may be formed using a liquid crystal injection method or a liquid crystal dispensing method.
For the liquid crystal injection method, a sealant having an inlet is formed on one of the lower and upper substrates, and the lower and upper substrates are bonded to each other. Then, liquid crystal is injected to a space between the lower and upper substrates through the inlet.
For the liquid crystal dispensing method, a sealant having no inlet is formed on any one of the lower and upper substrates, and liquid crystal is dispensed on any one of the lower and upper substrates. Then, the lower and upper substrates are bonded to each other.
As the size of substrate is increased, the liquid crystal injection method has the problem of low yield because the time for injecting the liquid crystal is too long. Accordingly, large panels generally use the liquid crystal dispensing method.
For the liquid crystal dispensing method, it is important to determine the appropriate amount of liquid crystal required. That is, for the liquid crystal injection method, there is no requirement to previously determine the amount of liquid crystal because the liquid crystal is injected into the space between the two substrates after bonding the two substrates to each other. However, the liquid crystal dispensing method requires a process for previously determining the amount of liquid crystal required because the two substrates are bonded to each other after dispensing the liquid crystal onto any one of the two substrates.
Currently, the amount of liquid crystal in the liquid crystal dispensing method is determined based upon the size and height of liquid crystal cell. However, it is difficult to determine the precise amount of liquid crystal need due to the various environmental conditions.
If an insufficient amount of liquid crystal is provided, unfilled regions may occur in the LCD panel, thereby degrading the picture quality. Meanwhile, if an excessive amount of liquid crystal is provided, overfilled regions may occur in the LCD panel, whereby the picture quality is degraded.
To minimize the unfilled or overfilled regions in the LCD panel, various methods for providing the exact amount of liquid crystal have been researched and studied. However, if unfilled or overfilled regions occur in the LCD panels, these LCD panels are discarded, thereby decreasing yield and increasing cost.
[MOVE???] FIGS. 2A and 2B are views for explaining the leakage of liquid crystal from a liquid crystal cell after forming an inlet for liquid crystal in a sealant, regulating the amount of liquid crystal, and sealing the inlet of liquid crystal, in sequence.
As shown in FIG. 2A, a liquid crystal cell is formed, wherein the liquid crystal cell includes a first substrate 100, a second substrate 200, a liquid crystal layer (not shown) formed between the first and second substrates 100 and 200, and a sealant 300 that surrounds the liquid crystal layer. If unfilled or overfilled regions occur, as shown in FIG. 2B, an inlet 350 for the inflow and outflow of liquid crystal is formed in the sealant 300, so as to regulate the amount of liquid crystal by discharging or supplying the liquid crystal through the inlet 350. As shown in FIG. 2C, the inlet 350 is sealed by a finish 400. At this time, because the finish 400 has a viscosity, as shown in FIG. 2C, the finish 400 may not get into the inlet 350. In this case, it is impossible to completely seal the inlet 350, whereby the liquid crystal provided inside the liquid crystal cell leaks to the outside.